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Isoproterenol treatment of Brown Norway and Lewis rats (high and low plasma angiotensin-I-converting enzyme activity, respectively) results in similar cardiac hypertrophy but higher cardiac fibrosis in Brown Norway rats. |
In the central nervous system, fibroblast growth factor (FGF)-20 has been reported to act preferentially on midbrain dopaminergic neurons. It also promotes the dopaminergic differentiation of stem cells. We have analyzed the effects of FGF-20 on human embryonic stem cells (hESCs) differentiation into dopaminergic neuro... |
Neurofibromatosis type 1 (NF1) is a common autosomal dominant disease characterized by formation of multiple benign and malignant tumors. People with this disorder also experience chronic pain, which can be disabling. Neurofibromin, the protein product of the Nf1 gene, is a guanosine triphosphatase activating protein (... |
Dorsal root ganglion (DRG) neurons have peripheral terminals in skin, muscle, and other peripheral tissues, and central terminals in the spinal cord dorsal horn. Hyperpolarization-activated current (I(h)) of the hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels are present in the DRG. The genes encodi... |
Occupational asthma is a form of immunotoxicity resulting from an exaggerated immune response to substances encountered in the workplace. Symptoms include reversible airway obstruction, airway hyperresponsiveness, airway remodeling, mucus production and cellular infiltration into the lung, particularly eosinophilia. Th... |
Allergen-specific IgE production is the central event in the pathogenesis of atopic disorders and increases in specific IgE serum antibodies are an indicator of immediate hypersensitivity responses in humans and in animal models of allergy. Consequently, accurate and user-friendly methods are needed to measure serum le... |
Indirubin-3-monoxime is an aryl hydrocarbon receptor (AhR)-binding, idole-derived compound known to be a potent inducer of CYP1A1, at least in hepatic cell lines. To date, very little is known about the effects of indirubin-3-monoxime on cells relevant to the immune system. We treated human U937 histiocytic lymphoma ce... |
Abundant literature exists demonstrating the immunomodulating effects of polychlorinated biphenyls (PCBs). To date, most of the research has focused on dioxin-like coplanar PCB congeners because of their high affinity for the aryl hydrocarbon receptor (AhR) and cytochrome P450-inducing capability. For this study, the i... |
The peak of erythropoietin-associated pure red cell aplasia (PRCA) incidents occurred over 4 years ago, but the debate on what triggered the autoimmune disorder continues today. The association with the recombinant human erythropoietin (epoetin, rhEPO) alpha-branded Eprex (Johnson and Johnson), makes PRCA of interest t... |
With the increasing number of biotherapeutic drugs entering clinical trials, drug-induced immunogenicity becomes more and more a topic in immunotoxicology of drug development. Immunogenicity relies on the induction or presence of antibodies recognizing a biotherapeutic protein after its administration. Anti-drug antibo... |
This review discusses currently available methods for predicting B-cell epitopes on proteins. The use of animals for assessing protein immunogenicity is addressed primarily to highlight the differences in B- and T-cell epitope recognition between species. These differences have to be considered when interpreting potent... |
With the recent increase in the approval and use of biotherapeutics in clinical practice, management of the development of anti-drug antibodies (ADA) has become a key issue for effective long-term use of these drugs. In most instances, the clinical benefit derived from the use of the therapeutics outweighs the risk of ... |
Immunogenicity is an important factor that manufacturers must consider as they develop new protein therapeutics. It is important to understand the immunogenicity of new proteins both at the preclinical phase and in the clinical phase of development. This paper provides an overview of the issues that manufacturers shoul... |
Tienilic acid (TA) was withdrawn due to idiosyncratic hepatotoxicity. Two hypotheses for the mechanisms of idiosyncratic reactions are the hapten and danger hypotheses, which are not mutually exclusive. Both human CYP 2C9 and rat CYP 2C11 metabolize TA to a reactive metabolite that was reported to bind exclusively to t... |
The fast development of biotechnology promotes the development of doping. From recombinant protein to gene doping, there is a great challenge to their detection. The improvement of gene therapy and potential to enhance athletic performance open the door for gene doping. After a brief introduction of the concept of gene... |
A method for the investigation on the interaction between bovine serum albumin (BSA) and liposome using capillary electrophoresis was developed. The oxidation index showed that the liposomes after freeze-drying were more stable. The results obtained from the capillary electrophoretic analysis of liposome showed that li... |
More than two thirds of the highly expressed ribosomal protein (RP) genes in Saccharomyces cerevisiae contain introns, which is in sharp contrast to the genome-wide five percent intron-containing genes. It is well established that introns carry regulatory sequences and that the transcription of RP genes is extensively ... |
An automatic spectrophotometric kinetic method for the microdetermination of chromium(VI) is described, based on catalysis of the hydrogen peroxide-iodide reaction. The time required for the reaction to produce a small fixed amount of tri-iodide is measured automatically, and is proportional to the chromium(VI) concent... |
A method has been described for the determination of concentrations below 10(-4)M by applying catalytic reactions and using thermometric end-point determination. A reference solution, identical with the sample solution except for catalyst, is titrated with catalyst solution until the rates of reaction become the same, ... |
Procedures are described for the accurate determination of silver (2-10 x 10(-7)M) and mercury(II) (2-10 x 10(-7)M) in the presence of each other and of most other metals. The methods are based on the inhibition by these metals of invertase catalysis of the hydrolysis of sucrose. |
In the absence of metal ions, the hydrolysis of 2-methyl-8-acetoxyquinoline and of 5-chloro-8-acetoxyquinoline follow the same reaction paths as those of the parent ester 8-acetoxyquinoline, including an intramolecular catalysis by the quinoline nitrogen. Unlike the hydrolysis of the other esters, that of the 2-methyl ... |
A silver wire immersed in a thiol solution gives a potential responsive to the thiol concentration, and is a sensitive indicator electrode in the potentiometric titration of thiols with mercury(II) chloride, p-chloromercuryphenyl sulphonate, and silver nitrate at pH 4.5-9.5, 7-9.5 and 9.5 respectively. Titrations of si... |
A kinetic study of the oxidation of some alcohols by xenon trioxide has revealed the optimum conditions for analysis of these alcohols. The rate of reaction may be increased by adding a catalyst or by increasing the pH of the solution; it may be decreased by adding an inhibitor. The initiation time of the reaction is u... |
Metal impurities in reactor cooling-water circuits must be kept to a minimum. A method is described for the determination of trace levels of cobalt in water samples, based on catalysis of the hydrogen peroxide oxidation of Alizarin Red S. The determination is carried out at pH 11.0 in a phosphate buffer under condition... |
Recent developments in the oxygen-flask technique for determination of phosphorus in coke are described. The existing method was modified by use of the recently proposed potassium antimonyl tartrate catalyst for the ascorbic acid reduction of phosphomolybdate. |
The range of acid concentration available for the titration of arsenic(III) with bromate is considerably extended by the use of osmium tetroxide as catalyst in preference to the use of hydrochloric acid or hydrochloric acid-potassium bromide media. The acid concentration range over which reaction is stoichiometric has ... |
A method of increased sensitivity for hydrogen enthalpimetry of olefins in mumole quantities is reported. The method depends on a linear relationship between the amount of alkene present and the heat given off on hydrogenation at slightly more than 2 atm pressure over palladium catalyst on charcoal. Least-squares analy... |
In the pseudotitration no reaction takes place between titrand and titrant in the bulk of the solution. An amperometric indicating system, which generates a small amount of redox catalyst in the vicinity of the electrode, does enable an end-point to be found. Bulk concentrations and diffusion constants are the controll... |
A discussion of the importance of the kinetic parameters, particularly the Michaelis constant K(m), in designing an analytical kinetic technique is given. The magnitude of K(m) is shown to affect only the range of substrate concentrations accessible and not the sensitivity of the method. The limitations and advantages ... |
An accurate method is described for determining the amount of active oxygen in manganese ores, based on the oxidation-reduction reaction between the ore and arsenic(III) in presence of ammonium molybdate, followed by the back-titration of excess of arsenic(III) with cerium(IV), using osmium tetroxide as catalyst and Di... |
Propyl mercaptan, allyl mercaptan, 2-mercaptoethanol, cysteamine hydrochloride, thio-p-cresol, 2-aminobenzenethiol, 2-mercaptopropionic acid and thioglycollic acid react with chloramine-T in 2:1 molar ratio in the presence of iodide, forming the corresponding disulphides. Mercaptans having a free beta-carbonyl group do... |
Peroxydiphosphate can be determined iodometrically in the presence of a large excess of potassium iodide with copper(II) or iron(II) as catalyst through the operation of the Cu(II)/Cu(I) or Fe(II)/Fe(III) cycle. The method is applicable in HClO(4), H(2)SO(4), HCl and CH(3)COOH acid media in the range 0.1-1.0M studied. ... |
The Co(III)-triethanolamine complex is recommended as catalyst in the chemiluminescence determination of hydrogen peroxide with luminol. |
Erioglaucine A, Eriogreen B, Patent Blue and Xylene Cyanol FF work satisfactorily for the titration of Sb(III) with Ce(IV) in 1-2N sulphuric acid medium with iodine as catalyst. In hydrochloric acid medium the colour of the oxidized dye is very evanescent but is very much improved in intensity and stability by the addi... |
A tensammetric method is proposed for the determination of microgram amounts of vanadium, based on catalysis of the oxidation of o-aminophenol with sodium chlorate in acidic solution (pH 2.0). The oxidation product gives a very sensitive tensammetric wave; under optimum conditions, the wave-height is proportional to th... |
Characterization of alumina-supported catalysts required determination of rhodium by atomic-absorption spectroscopy (AAS). Catalysts were loaded with 0.1-2.0% rhodium chloride and calcined at 400 degrees . Rhodium remaining as the chloride was regarded as the soluble form, while that converted into the oxide or bonded ... |
The determination of iodide with potassium dichromate and sodium vanadate in 6-8M phosphoric acid medium by potentiometric or visual titration is described. Ferroin and barium diphenylamine sulphonate (BDAS) are used as the indicators in the visual titration with potassium dichromate and sodium vanadate respectively. A... |
By means of catalytic analytical methods, extremely low levels can be determined at low cost and with a high sensitivity that is equal to that of physical methods of trace analysis. The selectivity of the catalytic determinations, is, however, usually rather lower than that of other methods of trace analysis. The selec... |
Trifluoperazine dihydrochloride reacts with platinum(IV) in sodium acetate-hydrochloric acid buffer containing copper(II) catalyst to form a bluish-green 1:1 complex with absorbance maximum at 504 nm. A 50-fold ratio of reagent to metal ion is necessary for complete complexation. Beer's law is valid over the concentrat... |
A catalytic method for the determination of copper, based on the catalysis of the hexacyano-ferrate(III)-cyanide redox reaction, is proposed. Experimental conditions to achieve the lowest detection limit are selected from the kinetics of both the catalysed and the uncatalysed reactions. The experimental measurements ca... |
A rapid sampling/mixing system has been designed which conforms to certain criteria necessary for its use as a clinical analyser. These include low solution volume (<100mul) for each determination on a sample, rapid cycle time (<2 sec to take an aliquot, mix and transfer reactants to an observation cell), good precisio... |
The influence of traces of O, N and C on the physical and especially the mechanical properties of the refractory metals Mo and W is discussed. The technological and economic importance of determination of O, N and C in Mo and W is elucidated. The Commission of the European Communities launched a relevant multidisciplin... |
A technique is described for the determination of catalytically active substances, in which a slow catalysed reaction is coupled to a fast competitive reaction. One reactant, which at the same time serves as the indicator substance, is removed by the slow reaction as well as by the competitor added to the system from o... |
A simple, sensitive and rapid colorimetric method is described for determining dimethoate [O,O-dimethyl-S-(N-methylcarbanoylmethyl)phosphorodithioate] and omethoate by an enzymatic method using pig liver acetone powder as enzyme source and p-nitrobenzenediazonium fluoroborate as the chromogenic reagent. This colorimetr... |
The mechanism of two indicator reactions, used for catalytic determination of copper-the oxidation of m-aminobenzoic acid and of 1,3,5-trihydroxybenzene by H(2)O(2)-was studied. It was found that, depending on the reaction conditions (reagent concentrations, acidity, temperature) the reactions can proceed according to ... |
The reduction of dissolved oxygen by SO(2-)(3) in feebly alkaline media is catalysed by Co(2+) ions. By use of an electrochemical sensor for oxygen, the optimum analytical conditions for determining traces of the catalyst have been established. At 25 degrees the optimum conditions are pH = 8.25 and [SO(2-)(3)] 1.25 x 1... |
The optimum conditions for the titration of antimony(III) with dichromate, and diphenyl-aminesulphonic acid as indicator, have been established. No iodine catalyst is used; the analytical reaction is based on an induced reaction with iron(II) as inductor. The titration can be done as easily as an iron(II) titration and... |
"Dimensionally Stable Anodes" (DSA)(R) have gained wide acceptance in electrochemical production of chlorine and caustic soda. The DSAs are usually composed of electrocatalytic layers of precious and non-precious metal oxides produced by thermal decomposition of salts on a valve-metal substrate (e.g., titanium). They h... |
The alkaline hydrolysis of the insecticide S-([6-chloro-2-oxo-3(2H)-benzoxazolyl]methyl)-O, O-diethylphosphorodithioate (phosalone) results in O,O-diethylphosphorothioate and 6-chloro-3-mercaptomethylbenzoxazolone. Phosalone and its hydrolysis products act as activators in the copper(II) catalysis oxidation of hydroqui... |
A simple enzymatic method is described for field TLC detection and determination of fenitrothion as fenitrooxon in water, with pig liver acetone powder as enzyme source. By this method, fenitrothion can be detected as fenitrooxon at ng levels and amounts ranging from 5 to 50 ng can be estimated. |
Data are presented for a refined spectrophotometric procedure for the simultaneous determination of zirconium and hafnium based on the combined effects of hydrogen peroxide, sodium sulphate, and excess of zirconium ion on the hafnium and zirconium complexes with Xylenol Orange in 0.2M perchloric acid. Isolation procedu... |
The titration of vanadium(IV) with cerium(IV) sulphate, with nitroferroin as indicator, is proposed. Unlike ferroin, the indicator does not need a catalyst in this system. By suitable choice of experimental conditions iron(II) can be titrated first to a ferroin end-point and then vanadium(IV) to a nitroferroin end-poin... |
A new technique for automated homogeneous immunoassay has been developed and applied to the determination of serum IgG. An enzyme label, horseradish peroxidase (HRP), conjugated to the antibody (anti-human IgG) was inhibited on immunochemical association. The inhibition of activity was monitored as a decrease in the la... |
A method for flow enthalpimetric determination of H(2)O(2) is described. The method uses manganese dioxide to catalyse the decomposition of H(2)O(2). The catalyst is stable enough to be used for at least 500 analyses. H(2)O(2) in the concentration range 0.01-10mM is determined with coefficients of variation < 2%. The m... |
The effect of metal ions on the reductive half-reaction of xanthine oxidase (XOD) in the catalytic conversion of xanthine into uric acid has been studied spectrophotometrically in Tris-HCl buffer at pH 7.4, 37 +/- 0.1 degrees and ionic strength 0.04M. Some metal ions display inhibitor properties, the sequence of inhibi... |
After semimicro Kjeldahl digestion of the coal sample with a K(2)SO(4)-V(2)O(5)-Se catalyst and sulphuric acid, the digest is cooled, diluted with water, neutralized and then made alkaline with NaOH/EDTA solution. The ammonia thus formed is determined by measuring the potential of a properly conditioned ammonia-sensiti... |
The reduction of Hg(II) at a glassy-carbon electrode in various electrolytes has been studied by rotating ring-disc voltammetry. Reduction proceeds directly to metallic mercury in a single 2-electron step. However, at the foot of the wave, and only during the first reduction sweep after pretreatment of the electrode su... |
The development of an enzyme-labelled immunoassay (EIA) of sufficient range and sensitivity for determination of plasma and salivary steroids is described. The method is based on competition in the solid phase. A fixed amount of a specific antibody is immobilized on polystyrene beads, its amount being enough to bind ab... |
Immunoassays based on europium labels and time-resolved fluorescence as the detection method, have been developed. The specific activity of the label is several orders of magnitude higher than that of radioactive labels. Consequently, the technique provides great potential, especially in the determination of analytes w... |
Manganese(IV) oxide electrodes formed with a graphite/PTFE substrate are shown to have near-theoretical response to manganese(II) ions in pH-4 acetate medium and a sub-Nernstian response in 0.1M nitric acid medium. Lead and iron(III) ions interfere, and iron(II) ions even more so, but other bivalent transition metal io... |
The inhibitory effect of selected metal ions [Ag(I), Hg(II), Cu(II), Cr(VI), V(V), Au(III), T1(I) and Zn(II)], on the xanthine oxidase (XOD) catalysis of xanthine oxidation, has been investigated with reference to the XOD catalysis of oxidation of NADH. Hg(II), Ag(I), Zn(II) and Au(III) act as inhibitors, T1(I) has no ... |
Precipitation and redox catalytic titration curves, obtained by both volumetric and coulometric addition of the titrant, have been simulated, taking into account the equilibrium concentration of the catalyst during the titration. The influence of several factors on the shape of the simulated catalytic titration curves ... |
Neutralization catalytic titrations of weak monoprotic adds and bases with both volumetric and coulometric addition of the titrant (strong base/acid) have been simulated by taking into account the equilibrium concentration of the catalyst during the titration. The influence of several factors on the shape of the simula... |
The catalytic nickel prewave produced by Cys-Gly, Cys-Tyr and Cys-Phe was studied in acetate buffer at pH 4-6.5. These peptides are more active than cysteine, especially the last two. The catalytic activity is depressed by decrease of pH owing to protonation of the catalyst. However, Cys-Phe and Cys-Tyr are still activ... |
A procedure is described for matrix modification in the determination of metals in blood by flame spectrometric methods. The protein is removed by precipitation with dilute nitric acid and centrifugation and the supernatant liquid is used for direct analysis. Nitric acid is compared with other acids as the precipitant.... |
An improved continuous-flow analysis method has been designed and applied to the determination of ultratrace amounts of cobalt(II) by the catalysis of the tiron-hydrogen peroxide reaction in basic medium. From 3 to 5000 pg of cobalt(II) in 1 ml of acidified sample can be determined at a sampling rate of 40 samples/hour... |
Amberlite IRA 900 anion-exchange resin modified with manganese-tetrakis(sulphophenyl)-porphine has been used as a catalyst instead of peroxidase for the determination of hydrogen peroxide by the reaction 2H(2)O(2) + N,N-diethylaniline + 4-aminoantipyrine (catalyst)--> quinonoid dye (lambda(max) 550 nm) + 4H(2)O. The ap... |
A new type of biosensor is introduced, based on a novel internal enzyme system which separates the sample solution from the analytical reaction. The bioanalyte diffuses through a gas-permeable membrane into the internal enzyme solution. A reaction that includes the bioanalyte is catalysed and the rate of this reaction ... |
Fluorine and chlorine in geological materials are volatilized by pyrohydrolysis at about 1150 degrees in a stream of oxygen (1000 ml/min) plus steam in an induction furnace. The catalyst is a 7:2:1 mixture of silica gel, tungstic oxide and potassium dihydrogen phosphate. The sample/catalyst mixture is pyrohydrolysed in... |
A high-pressure liquid chromatograph equipped with an off-column calorimetric reactor was used for the determination of metallorganic compounds such as metallothioneins. The stainless-steel gel-permeation column used was first tested with ultraviolet detection of a standard protein mixture. The metallothioneins were de... |
This paper describes the development of active materials for optically enhanced Raman and fluorescence spectroscopy. The substrates for surface-enhanced Raman scattering investigated in this study involved silver-coated microspheres on glass plates. The effect of various experimental parameters, such as angle of incide... |
Whenever proteins are found in environments different from those provided by physiological conditions, structural alterations can occur which can dramatically affect their adsorption and chromatographic behavior. The resultant behavior is often kinetically controlled and thus dependent on such factors as contact time o... |
Glucose oxidase (E.C. 1.1.3.4) is reversibly immobilized in a reactor coupled to a flow-injection analysis system using an immunological reaction. The antibody used is irreversibly immobilized on the reactor support by an avidin-biotin linkage. The bond between avidin and biotin is nearly irreversible under normal elut... |
3-Benzoyl-2-quinolinecarboxaldehyde has been synthesized and characterized for use as a precolumn fluorogenic reagent for the ultrahigh sensitivity determination of primary amines by micro-column liquid chromatography with laser-induced fluorescence detection. The reaction conditions and the spectral properties of the ... |
A kinetic potentiometric method is described for the determination of hydrazines (hydrazine, phenylhydrazine, hydralazine and procarbazine), isoniazid and sodium azide, based on monitoring their reactions at 25 degrees and pH 9.0 with 1-fluoro-2,4-dinitrobenzene by means of a fluoride-selective electrode. Initial-rate ... |
Room-temperature phosphorescence (RTP) spectra of eleven purines and pyrimidines adsorbed on Whatman No. 40 filter paper have been determined in acidic, neutral and basic media. RTP excitation and emission wavelengths do not vary significantly with pH. For most compounds, use of basic (pH approximately 13) solutions yi... |
The enantiomeric composition of carprofen has been determined in a rapid and reliable manner by proton nuclear magnetic resonance spectroscopy with a chiral lanthanide-shift chelate. Carprofen was converted into a mixture of enantiomeric methyl ester derivatives which were then complexed with tris[3-(heptafluoropropylh... |
A new type of flow-injection procedure is proposed in which the samples are reversely pumped to the detector. In this procedure the injected samples are pumped into the reaction loop of a 6-way valve, then the valve is rotated to reverse the flow and the sample/reagent plug is pumped to the detector by another pump. Th... |
An enzyme electrode for quantifying the total content of 3alpha-hydroxysteroids is described. 3alpha-Hydroxysteroid dehydrogenase (E.C. 1.1.1.50) was immobilized on the surface of glassy-carbon and low-temperature isotropic-carbon electrodes by intermolecular cross-linking with bovine serum albumin and glutaraldehyde. ... |
An enhanced chemiluminescence method for determining soluble and immobilized alpha-amylase has been developed, based on use of an insoluble amylose substrate labelled with horseradish peroxidase. Soluble peroxidase-labelled fragments of the substrate, released by the action of alpha-amylase, are quantified by the perox... |
A highly sensitive and novel polarographic method has been developed for determination of ultratrace amounts of osmium, based on the catalysis of the cerium(IV)-arsenic(III) reaction by osmium(VIII). The reaction rate is monitored by measuring the arsenic(III) with a single-sweep oscillopolarograph. Osmium concentratio... |
A new method for development of an electrochemical sensor based on lactate oxidase is dedbed. Platinized spectroscopic-grade graphite electrodes were modified by chemically cross-linking l-lactate oxidase from Pediococcus species into a poly(vinyl alcohol) network through reaction with a tri-isocyanate. The immobilized... |
Electrodes for amperometric measurement of l-glutamate were prepared by immobilization of l-glutamate oxidase on an Immobilon-AV Affinity membrane and attachment to an oxygen/hydrogen peroxide sensor. The response of the hydrogen peroxide sensor was linear over the concentration range 5.0 x 10(-8)-5.0 x 10(-4)Ml-glutam... |
Glucose oxidase modified by the covalent attachment of ferrocenecarboxylic acid or ferrocene-acetic acid groups undergoes direct oxidation at metal electrodes. Studies of the comparative stability of the two modified enzymes on storage and on electrochemical cycling show that the material modified with ferroceneacetic ... |
The modification of carbon-paste electrodes by incorporation of the enzyme glucose oxidase (GOD) is described. The resulting probes can be operated as amperometric glucose sensors in the presence or absence of a mediator (1,1'-dimethylferrocene) mixed into the paste. Extended linear calibration ranges have been obtaine... |
A flow-injection system is described that incorporates a small column reactor containing two co-immobilized, synergistically operating oxidoreductases, allowing determination of minute amounts of substrates by means of enzyme amplification and subsequent chemiluminescence detection of the hydrogen peroxide generated in... |
A general assay procedure for a wide variety of thiols is described. The technique has three steps: (1) formation of S-nitrosothiols with nitrous acid, (2) destruction of the excess of nitrous acid, (3) hydrolysis of the S-nitrosothiols with mercuric ions and subsequent formation of an azo-dye by means of the nitrous a... |
An automated method for the determination of small amounts of proteolytic enzymes has been developed, by combining a stopped-flow and an on-line preconcentration technique, using sorbent extraction. It is based on the hydrolysis of a synthetic chromogenic substrate during the stopped-flow period, yielding p-nitroanilin... |
A sensitive and inexpensive method of spectrophotometric determination of chromium(VI), based on the absorbance of its complex with malachite green and acetic acid at pH 2.5 is reported. The complex shows a molar absorptivity of 8 x 10(4) l.mole(-1) cm(-1) at 560 nm, using malachite green and acetic acid as reference s... |
Biosynthetic human Growth Hormone (B-hGH) is a protein comprising 191 amino acids. The molecular weight is 22,125 and the isoelectric point is close to pH 5. Due to the ready availability of closely related analogues B-hGH was used as a model protein thus allowing for the demonstration and evaluation of the high resolu... |
The combined effects of micellar and chemical catalysis were studied with a view to improving the features of catalytic kinetic determinations. For this purpose we chose the reaction between N,N-dimethyl-p-phenylenediamine (DPD) and N,N-dimethylaniline (DA) to form Bindschedler's Green leuco base, which is oxidized by ... |
The secondary structure of purified protamine, a non-specific DNA binding protein, was studied in solution at pH 4, 7 and 8 by FTIR. This permitted analysis of the folded form of the protein (acidic pH) as well as the folded conformers (neutral and basic pH). Hg(2+) was utilized to probe the accessibility of the free t... |
The voltammetric behavior of amaranth at a mercury thin film electrode on a silver substrate was studied in this paper. It was found that amaranth gave a sensitive reduction peak with the potential of -0.24 V at pH 4.0 in aqueous solution. The mercury thin film electrode on a silver substrate gave good reproducibility ... |
A cyclic reaction between the reduced and the oxidized forms of vitamin C takes place by combining the ascorbate oxidase reaction and the reduction of l-ascorbic acid to dehydroascorbic acid by dithiothreithol. l-Ascorbic acid is oxidized by the dissolved oxygen and its consumption is not compensated by the chemical re... |
Inhibition of the enzyme acetylcholinesterase (AChE) using a carbamate compound was measured in 30 Crl: CD(R)BR Sprague Dawley rats. Erythrocyte, plasma, and brain tissues were analyzed using modifications of the Ellman technique(1) on two different clinical chemistry analyzers. Both EDTA and heparin anticoagulated who... |
Water sorption isotherms were obtained on surface acoustic wave sensors (SAWS) coated with aminopropyltriethyoxysilane (APTES), and on uncoated SAWS of which the substrate material was polished ST-quartz. The isotherms were obtained at 25 degrees , 30 degrees and 40 degrees over the range 1-80% relative humidity (RH). ... |
A sensitive and rapid method for the estimation of trace levels of indium in alumina supported catalysts using square wave voltammetry (SWV) is discussed. The SWV method for indium in the alumina matrix is standardized using synthetic samples and good recoveries were obtained. Calibration graphs are linear in the range... |
In the framework of a certification campaign organized by BCR (Bureau Communautaire de Référence, Commission of the European Communities, Brussels) molybdenum was determined in a sea water candidate reference material (BCR CRM 403) using inductively coupled plasma-mass spectrometry. The determination was hampered by bo... |
A spectrophotometric flow injection method for the determination of H(2)O(2) in aqueous solution is presented. The technique is based on the oxidative condensation reaction between 1-anilinonaphthalene-8-sulfonic acid (ANSA) and 4-aminoantipyrine (AAP) in the presence of H(2)O(2). Hematin is a good peroxidatic catalyst... |
The performance and analytical characteristics of a glassy carbon glutaraldehyde immobilized glucose oxidase electrode have been established with regard to the direct detection of hydrogen peroxide produced from the reaction of glucose with oxygen. Measurements were performed at + 1.1 V vs. SCE, and selectivity was obt... |
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